This invention relates to an expansion body for constructions located in the earth including a folded elongated casing and a first and a second closure arranged at the upper and lower end respectively of the casing, said casing and closures defining an internal closed space connectable to a source of pressurized fluid for the expansion of the body by pressing out the folds of the casing.
Expansion bodies of the kind mentioned above have been proposed for in situ piles and especially as an expanded foot of these. When such piles are used, the casing is first inserted into the ground and then filled with pressurized water or concrete for pressing out the folds thereof thus giving the pile its final shape.
A problem related to expansion bodies of that kind has been the arrangement of the end closures. The reason for this is that said closures must be designed for sealing the end parts of the casing as well as for enabling the foldings to unfold gradually from the ends without causing cracking tensions in the casing. According to one known proposal for such an expansion body, the closures are shaped like cone-formed endings of the casing with successively decreasing depths of the foldings. Closures like that are, however, in practice impossible to manufacture for a reasonable cost. They are also unsuitable for closely folded casings or when there is a need for larger inlets or tubes leading through the casing.
An object of the present invention is to provide an expansion body with end closures which eliminate the drawbacks mentioned above. Another object is to provide an end closure which is simple and cheep to manufacture and mount on the ends of the casing.
These objects and others are achieved by providing an expansion body according to the accompanying claims.